Add AudioStreamRegistry. Move stream counting logic

content/browser/renderer_host/media/audio_stream_registry_impl.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/renderer_host/media/audio_stream_registry_impl.h"
+
+#include <algorithm>
+#include <utility>
+
+#include "base/lazy_instance.h"
+#include "base/metrics/histogram_macros.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_process_host.h"
+#include "media/audio/audio_streams_tracker.h"
+
+namespace content {
+
+namespace {
+
+base::LazyInstance<media::AudioStreamsTracker> g_audio_output_streams_tracker =
+    LAZY_INSTANCE_INITIALIZER;
+
+void NotifyRenderProcessHostThatAudioStateChanged(int render_process_id) {
+  DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+  RenderProcessHost* render_process_host =
+      RenderProcessHost::FromID(render_process_id);
+
+  if (render_process_host)
+    render_process_host->AudioStateChanged();
+}
+
+}  // namespace
+
+AudioStreamRegistryImpl::AudioStreamRegistryImpl(int render_process_id)
+    : render_process_id_(render_process_id) {}
+
+AudioStreamRegistryImpl::~AudioStreamRegistryImpl() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(output_streams_.empty());
+  DCHECK(stream_currently_playing_.empty());
+
+  if (max_simultaneous_output_streams_ > 0) {
+    UMA_HISTOGRAM_CUSTOM_COUNTS("Media.AudioRendererIpcStreams",
+                                max_simultaneous_output_streams_, 1, 50, 51);
+    UMA_HISTOGRAM_CUSTOM_COUNTS(
+        "Media.AudioRendererIpcStreamsTotal",
+        g_audio_output_streams_tracker.Get().max_stream_count(), 1, 100, 101);
+    g_audio_output_streams_tracker.Get().ResetMaxStreamCount();
+  }
+}
+
+// static
+AudioStreamRegistryImpl::UniquePtr AudioStreamRegistryImpl::Create(
+    int render_process_id) {
+  return {new AudioStreamRegistryImpl(render_process_id), {}};
+}
+
+bool AudioStreamRegistryImpl::HasActiveAudio() {
+  return !base::AtomicRefCountIsZero(&num_playing_output_streams_);
+}
+
+#if BUILDFLAG(ENABLE_WEBRTC)
+void AudioStreamRegistryImpl::EnableDebugRecording(
+    const base::FilePath& base_file_name) {
+  if (!debug_recording_path_.empty()) {
+    // There is already a recording in progress.
+    DisableDebugRecording();
+  }
+  debug_recording_path_ = base_file_name;

[o1ka, 2016/12/22 10:46:52]

Thread safety?

[Max Morin, 2017/01/09 15:34:23]

Done.

+  for (Stream* stream : output_streams_)

[o1ka, 2016/12/22 10:46:52]

Thread safety?

[Max Morin, 2017/01/09 15:34:23]

Done.

+    stream->EnableDebugRecording(base_file_name);
+}
+
+void AudioStreamRegistryImpl::DisableDebugRecording() {
+  debug_recording_path_.clear();
+  for (Stream* stream : output_streams_)
+    stream->DisableDebugRecording();
+}
+#endif  // BUILDFLAG(ENABLE_WEBRTC)
+
+void AudioStreamRegistryImpl::RegisterOutputStream(Stream* stream) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  bool did_insert = output_streams_.insert(stream).second;
+  DCHECK(did_insert);
+
+#if BUILDFLAG(ENABLE_WEBRTC)
+  if (!debug_recording_path_.empty())
+    stream->EnableDebugRecording(debug_recording_path_);
+#endif  // BUILDFLAG(ENABLE_WEBRTC)
+
+  max_simultaneous_output_streams_ =
+      std::max(max_simultaneous_output_streams_, output_streams_.size());
+  g_audio_output_streams_tracker.Get().IncreaseStreamCount();
+#if DCHECK_IS_ON()
+  stream_currently_playing_.insert(std::make_pair(stream, false));
+#endif
+}
+
+void AudioStreamRegistryImpl::DeregisterOutputStream(Stream* stream) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  size_t num_erased = output_streams_.erase(stream);
+  DCHECK_EQ(num_erased, 1u);
+
+  g_audio_output_streams_tracker.Get().DecreaseStreamCount();
+#if BUILDFLAG(ENABLE_WEBRTC)
+  if (!debug_recording_path_.empty())
+    stream->DisableDebugRecording();
+#endif  // BUILDFLAG(ENABLE_WEBRTC)
+
+#if DCHECK_IS_ON()
+  DCHECK(!stream_currently_playing_.at(stream));
+  stream_currently_playing_.erase(stream);
+#endif
+}
+
+void AudioStreamRegistryImpl::OutputStreamStateChanged(Stream* stream,
+                                                       bool playing) {
+#if DCHECK_IS_ON()
+  auto it = stream_currently_playing_.find(stream);
+  DCHECK(it != stream_currently_playing_.end());
+  DCHECK(it->second != playing);
+  it->second = playing;
+#endif
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);

[o1ka, 2016/12/22 10:46:52]

Thread check first, then access stream_currently_playing_?

[Max Morin, 2017/01/09 15:34:23]

Done.

+  if (playing) {
+    base::AtomicRefCountInc(&num_playing_output_streams_);
+
+    // Inform the RenderProcessHost when audio starts playing for the first
+    // time. The nonatomic increment-and-read is ok since this is the only
+    // thread that |num_playing_output_streams_| may be updated on.
+    if (base::AtomicRefCountIsOne(&num_playing_output_streams_)) {
+      BrowserThread::PostTask(
+          BrowserThread::UI, FROM_HERE,
+          base::Bind(&NotifyRenderProcessHostThatAudioStateChanged,
+                     render_process_id_));
+    }
+  } else {
+    // Inform the RenderProcessHost when there is no more audio playing.
+    DCHECK(!base::AtomicRefCountIsZero(&num_playing_output_streams_));
+    if (!base::AtomicRefCountDec(&num_playing_output_streams_)) {
+      BrowserThread::PostTask(
+          BrowserThread::UI, FROM_HERE,
+          base::Bind(&NotifyRenderProcessHostThatAudioStateChanged,
+                     render_process_id_));
+    }
+  }
+}
+
+// static
+void AudioStreamRegistryImpl::DetachAudioStreamsTrackerFromThreadForTesting() {
+  g_audio_output_streams_tracker.Get().DetachFromThreadForTesting();
+}
+
+}  // namespace content